The invention relates, generally, to Internet protocol (IP) communication systems and, more particularly, to a communication system that uses ATM switches as routers and ATM standards and existing IP protocols to efficiently route IP traffic.
It will be appreciated that the Internet consists of routers owned by Internet Service providers (ISPs) and/or corporate, educational or other information centers (ICs). The routers are connected by lines that are typically leased from telecommunication companies. Because of the phenomenal growth by the Internet in recent years a tremendous burden is presently being placed on the conventional telecommunications infrastructure to handle Internet traffic.
One existing technology designed to carry voice, data and video is asynchronous transfer mode (ATM) technology. Standard ATM technology packs data into cells where each cell is 53 bytes long consisting of a 5 byte header and a 48 byte payload. The packets are transmitted over virtual channels and virtual paths between destination and source end points as will be understood by one skilled in the art. IP traffic using ATM is packet switched such that each router in the network must examine every packet and the router""s controller must perform a flow classification on each cell based on the header address. Because the router controller must examine every packet, the flow classification process creates a bottleneck in the flow of packets thereby decreasing the overall efficiency of the network.
In an effort to eliminate this problem, ATM switch protocols that allow the IP packet traffic to xe2x80x9ccut-throughxe2x80x9d the ATM switch such that the packets bypass the controller and travel through the switch at ATM hardware speed have been developed. Examples of such systems are the Ipsilon Networks, Inc. IP Switch, IBM""s Aggregate Route-based IP Switching (ARIS) product and Cisco Systems, Inc. tag switching product. While these systems utilize ATM hardware to effectuate the cut-through path, they do not realize the full benefits of ATM routing functionality. For example, these systems use proprietary protocols to set up cut-through paths. As a result, IP traffic cannot be routed between the switches and routers that are based on different proprietary protocols. Some of these systems also require flow classification of the IP traffic where only certain types of traffic are cut-through. One problem with such systems is that the number of flows could outstrip the number of available virtual circuits. Finally, the known systems, although using ATM hardware, do not make use of ATM software and functionality such that the known systems do not provide ATM QOS (quality of service) end to end.
Thus, an improved system for allowing IP traffic to xe2x80x9ccut-throughxe2x80x9d ATM switches is desired.
The system of the invention separates incoming traffic between traffic that is to be handled by the receiving router and traffic that is to be forwarded to other network elements from the receiving router. Traffic that is to be handled by the receiving router uses classic IP over ATM to route the traffic to the appropriate destination by providing a flow classification of each packet by the router controller as is known. Traffic that is to be forwarded to other routers from the receiving router uses ATM standards to set up switched virtual paths (SVPs) cutting through network elements. The path setup is switched virtual path (SVP) where different traffic flows can use different virtual channel identifiers (VCIs) on the same SVP. The routing capabilities of Private Network-Network Interfaces (PNNI) and eventually Integrated Network-Network Interfaces (IPNNI) can be used when setting up the common SVPs. The virtual router of Multi-Protocol Over ATM (MPOA) can also be used. Because the overhead of setting up a SVC is typically too great to justify one SVC per flow, SVPs are used. In addition, after a cut-through path is set up, it is reused.